The main goal of this project is to investigate the pulsatile nature of growth hormone and prolactin secretion in patients with pituitary adenomas. The relatively short half-life of these peptides in the circulation and the fact that they are secreted in pulses, limits interpretation of, and the physiologic significance of single hormone measurements. Recent studies have demonstrated the pulsatile nature of growth hormone and prolactin secretion in humans. Similar studies have not been conducted in patients with functioning or non functioning adenomas especially after surgical adenomectomy. We currently rely on pituitary hormone dynamic studies in the detailed evaluation of patients with adenomas and in assessing the long term outcome after surgery. While this approach has been very useful, the responses may not be representative of normal physiology. Investigating pulsatile hormone secretion in these patients should provide additional physiological significance to the dynamic studies. We have already determined the pulsatile pattern of hormone secretion in healthy individuals and will use the data for comparison to that of patients with pituitary adenomas. The current study will be limited to patients with adenomas, studied before or after surgery. Though limited, the data show pulsatile prolactin release in patients with adenomas. The pulse frequency was, however, decreased when compared to normal individuals. After successful surgical treatment, pulse frequency and amplitude are similar to normal. After surgery, there was a relative increase in nocturnal release of prolactin such that the ratio of night/day levels was similar to that of normal. A total of 11 patients with known pituitary adenomas have already been studied. Six were studied before surgery while five others were evaluated months to years postoperatively. Publication of the data will be delayed until more surgically treated patients are studied.